UpLifting

Lesser forms of internal combustion, known to most as gasoline engines, often teeter on the edge of airflow, fuel flow, and ignition advance. At elevated cylinder pressure, an air/fuel ratio or timing curve that’s just slightly off the mark can turn forged rotating assemblies into forged bits of shrapnel. By taking spark timing out of the equation, however, diesel engines live in an auto-ignition utopia where deadly detonation is never an issue. Cylinder pressure and fuel flow decide when to get the combustion party started all on their own.

Given this glorious dynamic, dumping obscene volumes of boost into the cylinders—and laying down 1,000 lb-ft of torque like a boss—is the only logical thing to do. Nevertheless, in order to maximize horsepower and torque, air and fuel must increase in equal measure. If plans call for a monster turbocharger upgrade, you better make sure the fuel pump can keep up. With Aeromotive’s new lift pump kits for Power Stroke and Duramax diesel engines, meeting the fueling demands of even the biggest of turbos is cake.

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| The 6.0L Power Stroke engine in Richard Alvarado’s ’06 Ford F-250 has seen many different parts combinations in its day, with a recent upgrade from a BorgWarner S367 turbo and 250/100 injectors to the current SX-E 369 ’charger and 330/150 injectors. Although horsepower increased from 715 to 736 with these upgrades, Richard feels more oomph is available through a fuel pump swap.

Making It Official

Although extremely well known on the gas side of the street/strip arena, Aeromotive is a relatively new player in the diesel market, at least officially. Long before the company decided to build diesel-specific products, customers were already using its pumps on their diesel rigs. “Over the years, our A1000 inline fuel pump has been used in automotive, military, commercial, and marine applications. People started using the A1000 in diesels, and even though it was never engineered for diesel applications, it still worked very well,” Brett Clow of Aeromotive explains. “The diesel-performance market continues to grow, and at the same time, diesel fuel has changed a lot in recent years, with low-sulfur formulations and bio additives. We realized that in order to have a serious presence in the diesel market, we needed to design products specifically for diesel-powered vehicles.”

Interestingly, unofficial uses of Aeromotive pumps in oil-burning applications inspired the company to enter the market with a diesel-specific design. By closely analyzing how well the A1000 pump performed—and where it fell short—in environments it was never designed for, Aeromotive set out to create the ultimate diesel lift pump. “Diesel has different dielectric properties than gasoline, so it conducts more electricity,” Brett reveals. “This caused the copper commutators and brush assembly to wear out more quickly than we wanted in our A100 pump. To correct this premature wear, we developed a brushless motor that eliminates conductivity.”

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| In an effort to control pressure spikes, the engine is already fitted with an Aeromotive bypass pressure regulator. Since the new pump features an integrated regulator, Richard removes this old unit and reroutes the lines accordingly.

Not surprisingly, the battle-tested design features of Aeromotive’s gasoline pumps are carried over to the company’s new diesel product line. “At Aeromotive, we prefer inline-pump designs because they remove the motor shaft from the flow path of fuel. This results in a very efficient pump and eliminates shaft seals, which are usually prone to leaking,” Brett says. “By running a wet motor inside the pump case and sealing it with O-rings, we can minimize the potential for failure. As with all of our pumps, we wanted to create a system that’s very well thought out and easy to install.”

One-Two Punch

One of the most unique aspects of Aeromotive’s approach to its lift-pump design is that it doesn’t actually replace the stock pump. Instead, it supplements the stock pump so both can tag-team fuel-delivery duties. “Running the Aeromotive pump and the stock lift pump in parallel allows the fuel system to support more horsepower. Instead of eliminating the stock pump, we augment it with a second pump to create a more efficient fuel system,” explains Brett.

If you’re still scratching your head, here’s how it works. Both pumps draw fuel from their own pickup tubes in the tank. The stock pump’s outlet line is then rerouted to the Aeromotive pump. There, the cumulative fuel flow of both pumps merge together and exit through the same outlet that feeds the supply line running to the fuel rails. “In addition to increased flow advantages, the redundancy of having two parallel pumps improves reliability. Towing one of these big trucks is not cheap. If the stock pump fails, you can easily drive home on the Aeromotive pump. In the unlikely scenario where our pump stops working, the stock unit can still flow through our pump so you won’t be stranded on the side of the road.”

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| Aeromotive’s lift pump (PN 11808) for ’03-to-’07 6.0L Power Stroke diesels moves 130 gph of fuel at 10 psi. Assuming a conservative .500 brake-specific fuel consumption (BSFC), the pump will easily support 1,400 flywheel horsepower. This figure does not take into account the additional fuel flow provided by the stock pump. The complete lift pump kit retails for a little less than $2,000. GM Duramax (PN 11801) and ’08-to-’10 Power Stroke kits (PN 11807) are available as well.

Regulators

Pressure spikes in any fuel system are bad, but at the elevated line pressure under which diesels operate, their effects are even worse. “Each time the spillover ports in the injectors sweep closed, it allows air and high-pressure fuel to go back into the rail and spike,” Brett says. “These pressure pulsations are very hard on the fuel pump. Ford installed check valves on the cylinder heads to protect the fuel system from these spikes. The problem is that once you upgrade to bigger injectors, the spikes get even worse. Installing a pressure regulator can help, but if it’s positioned after the cylinder head, the fuel pump is still exposed to these pressure spikes. If you’re running 60 psi of line pressure, these spikes can easily hit 120 psi. To address this issue, we integrated a pressure regulator right into the head of our new fuel pump. This provides a cushion that protects the fuel pump from pressure spikes.”

Separation Anxiety

Dude, where’s the air-separator filter? What seems like a glaring oversight on the surface is actually the product of some clever engineering. “Most of the air in a fuel system comes from how the fuel is picked up from the tank,” Brett explains. “Every hard 90-degree turn in the fuel lines creates a pressure drop on the trailing edge of the bend. These low-pressure areas can vaporize the fuel, which creates bubbles and causes cavitation. To limit cavitation, our pickup tube has smooth mandrel bends. It also draws fuel through a 100-micron screen and a well-thought-out baffling system. With this design approach, we don’t need to worry about separating the air, because we don’t introduce air into the fuel in the first place. By eliminating the source of cavitation, we eliminate the need for an air separator filter.”

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| The integrated pressure regulator allows excess fuel to bypass directly through the pump body and back into the tank. Richard sets the pressure at 63 psi. Aeromotive prides itself on designing regulators around the needs of each of its fuel pumps. Although the company won’t reveal its trade secrets, tailoring regulator design to a specific fuel pump model helps maintain steady pressure even as an engine’s fuel consumption increases.

Built for Boost

Regardless of how great a fancy block of billet looks on paper, the true merit of any product is how well it performs in the real world. After installing Aeromotive’s lift pump on an ’06 Ford F-250 and running the truck on PSP Diesel’s Mustang dyno, we can confidently vouch for the new unit.

Shop co-owner Richard Alvarado’s F-250 is a mean daily driver that packs more than enough boost to warrant a monster fuel pump. Force-feeding the 6.0L Power Stroke engine is a BorgWarner SX-E 369 turbo that gets spooled up by a Steed Speed exhaust manifold. The cold side ingests air through a No Limit Fabrication air-intake assembly, then directs 62 psi of boost to a Banks Power intercooler and a ported ODawgs Diesel Performance intake manifold. Holding the long-block together are Carrillo connecting rods, heavy-duty wristpins, Mahle pistons, O-ringed stock cylinder heads, and ARP main and head studs.

With a set of Warren Diesel Injectors 330/150 injectors, a Thumper II high-pressure oil pump, and an SCT 5015 programmer managing the fuel supply, the engine made 736 hp and 1,083 lb-ft during our baseline dyno run. Although those figures are pretty darn impressive, Richard suspected the stock lift pump was leaving some horsepower on the table. “Anytime you install modified fuel injectors, you want to upgrade the lift pump as well. You can install every bolt-on in the book, but it won’t do anything without the proper tune and fuel upgrades,” he advises.

Practicing what he preaches, Richard dropped the F-250’s fuel tank and installed the new lift pump. “The Aeromotive lift pump is very nice and easy to set up and install. I really like the quality of the pickup screen and the sponge baffle, which will keep a lot of debris out of the fuel system,” Richard reports. Once the truck rolled back onto the dyno, output surged to 785 hp and 1,272 lb-ft of torque. For a rig that’s already making a lot of steam, picking up 49 hp and 189 lb-ft isn’t too shabby for a day’s work.

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| The 2-micron Caterpillar 1R-0750 filter can remove the tiniest of contaminants, and the pump’s standard 1x14 thread makes it compatible with various brands of filters as well. The pump’s body features an AN -12 inlet port, and AN -10 outlet and return ports.

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| Most baffle assemblies are designed to keep the pump’s pickup submerged when fuel sloshes around the tank at low fuel levels. Aeromotive goes one step further by adding a foam core that filters out air bubbles to reduce cavitation.

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| In addition to the pump filter, the system includes a 100-micron in-tank filter to capture larger contaminants. The replaceable filter element is attached to a slick billet-aluminum housing that clamps onto the pickup tube.

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| Although there is no practical way to avoid a 90-degree turn in the fuel pickup, the tube is mandrel bent to significantly reduce pressure drop and cavitation. An adjustable collar makes changing tubing height easy.

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| When servicing the fuel system, it’s always a good idea to disconnect the battery and to relieve pressure from the lines by removing the tank’s cap. Dropping the tank is a straightforward affair that’s much easier with an extra set of hands. After disconnecting the stock fuel lines, wiring harness, and tank straps, the entire assembly drops right out. Centering a jack beneath the tank helps stabilize it during descent.

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| A 1-inch hole for the new pickup tube should be drilled far enough away from the stock sending unit so the baffle does not contact the float arm. The ¾-inch hole for the return tube must be drilled 2.5 to 3 inches away from the pickup tube. Measuring tank depth is necessary in order to trim the pickup tube to the correct height.

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| Adding an inch to the tank depth height (13.5 inches total) establishes the correct height of the pickup tube. If it’s still too tall, it can be further trimmed. A tubing cutter makes quick work of the cutting process.

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| The baffle assembly must be centered directly beneath the pickup tube. The return tube is designed to sit between the foam and black rubber basket. As such, it needs to be trimmed so the end of the tube rests halfway between the top and bottom of the basket. The J2044 bulkhead connector for the return tube attaches to the underside of the tank with a PTFE washer and lock nut.

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| With the pickup inserted into the tank, the filter is clamped down onto the tubing. Similar to the return tube, the pickup attaches to the underside of the tank with a PTFE washer and a lock nut.

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| Before reinstalling the stock sending unit, ensure the float arm swings freely. Otherwise, the fuel-level gauge will not work properly. A locking collar prevents the top of the pickup from swiveling around. With the tank buttoned back up, the size difference between the stock and Aeromotive pickup tubes is dramatic.

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| Routing the new feed and return lines inboard along the driver-side framerail provides a direct path to the new lift pump. Securing the hoses to the frame with zip ties keeps them out of harm’s way.

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| After mounting the new pump, connecting the feed, return, and suction lines is a simple push-in affair. The suction and return lines (red) are located on the left side of the pump. On the opposite side, one line connects the stock pump—mounted beneath the driver-side floorboard—to the Aeromotive pump. The port on the regulator outlet (right) attaches to the engine-feed line.

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| Wiring the Aeromotive pump is as idiot-proof as it gets. The supplied harness simply plugs into the fuel pump on one end and the battery on the other end. The harness includes a relay, as well as a mini-fuse tap that plugs into a switched ignition slot in the fuse box.

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| Before making hits on the dyno, the final step of the installation process involves checking for leaks. Since the Aeromotive pump is a self-priming unit, there’s no need to perform a formal priming procedure. With the leak check complete, it’s finally time to make some power!